A walk in the park is more than just a nice way to spend an afternoon; it could also help city dwellers fight off sickness and depression.

If you've ever remarked that you feel happier on a sunny day, or felt yourself becoming snarky and glum when you'd been trapped inside all day, you've already seen anecdotal proof of the environment's healing powers.

Now, new research at the University of Illinois has confirmed this folklore, showing that time spent in green, outdoor spaces is an essential component for good health.

"Through the decades, parks advocates, landscape architects, and popular writers have consistently claimed that nature had healing powers," said U of I environment and behavior researcher Frances "Ming" Kuo. "But until recently, their claims haven't undergone rigorous scientific assessment."

As director of the Landscape and Human Health Laboratory at the University, Kuo has spent a great deal of time studying the effect of green space on humans in a number of settings. She says that over the past decade or so, research into the therapeutic effects of time in nature have become more rigorous and impressive.

By contrast, environments with less green space are associated with greater rates of childhood obesity; higher rates of 15 out of 24 categories of physician-diagnosed diseases, including cardiovascular diseases; and higher rates of mortality in younger and older adults.

Because of this strong correlation between nature and health, Kuo encourages urban planners to design communities with more public green spaces in mind, not as mere amenities to beautify a neighborhood, but as a vital component that will promote healthier, kinder, smarter, more effective, more resilient people.